To say children do not have rights is wrong because everyone was a child at some point. I think spanking should be banned because it is emotionally traumatizing to children. Children never speak back to their parents when this happens and I think parents need to figure out a better way to discipline their children without harming them physically.
E.G. In Germany even a 17yo can't buy a damn Snickers if his/her parents prohibit it. Parents are responsible for the education of their children and therefor HAVE to proxy-administer some of a childs rights. They decide where the child lives, whom it is accompanied by, which school they attend or not and so on.
You may be against child spanking. It's your given right to think so. But, legally speaking, children and adults are not equal. Therefor: Basing a spanking ban on this (falsely) presumed equality is as stupid as never spanking your children.
Because the adult is accountable for the actions of the child, it is by necessity that the adult assumes some of the rights of the child, save the ones gained by attaining the age of majority, which are held in nonexistence until granted by that simple flip of the calendar.
Children do not have the same rights as adults. Ideally, children should have the same rights but in actuality they just do not. The world is not a fair place. Children cannot pick or choose the family in which they are born. The rights each child has vary according to the environment they are brought into just as the rights of individual adults vary as well.